Information storage system including a plurality of storage systems that is managed using system and volume identification information and storage system management method for same

ABSTRACT

An embodiment of this invention is an information storage system comprising a plurality of storage systems connected to be able to communicate. Each of the plurality of storage systems includes default storage system identification information which is the same to the plurality of storage systems, common volume identification information for uniquely identifying volumes provided by the plurality of storage systems to a host computer among the plurality of storage systems, and a controller configured to return the default storage system identification information to the host computer in response to a request from the host computer and to process a read or write request to a volume accompanying the common volume identification information from the host computer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/129,556, filed on May 16, 2011, which claims the benefit ofPCT/JP2011/002486 filed on Apr. 27, 2011, which are incorporated byreference as if fully set forth.

TECHNICAL FIELD

This invention relates to an information storage system and a storagesystem management method and, in particular, relates to a managementtechnique of a plurality of storage systems.

BACKGROUND ART

Recent drastic increase in the amount of information handled bycomputers promotes expansion of the scale of data centers hosting hostcomputers and storage systems for processing information. Servers,storage systems, and networks installed in data centers have attainedtechnological progress to reduce management costs on an individualapparatus basis.

For servers, with enhancement of performance in units of apparatus, anarchitecture implementing a virtualization mechanism in ahighly-integrated blade-type apparatus is beginning to be employed toachieve load balancing among a plurality of servers. To storage systems,a design that stores consolidated massive data in a large-scaled storagesystem with high performance, high reliability, and high availability isapplied, instead of storing massive data in a number of small storages.As to network equipment, increasing the number of connections perapparatus improves performance to bear increased traffic among systems.

In such circumstances, data centers come to face a problem of managementcost for procuring individual apparatuses and constructing and operatinglarge-scale systems. To reduce the cost, integrated systems includingbuilt-up systems with servers, storages, and networks are beginning tobe proposed.

Such an integrated system includes built-up components of servers,storage systems, and networks with determined specifications;accordingly, if it is assumed to use it within the range of itsspecified performance, construction and operation costs can be reduced.

An issue to improve the system performance is management of storagesystems. Because of difficulties in designing performance and capacity,and difficulties in building up a storage area network (SAN), alarge-scale data center employs an administrator specialized in thestorage system; accordingly, simplification is particularly desired andtechniques are under development.

One of the techniques to achieve a large-scale storage system is astorage area network. A storage area network connects one or morestorage systems to a plurality of host computers so that a plurality ofhost storages can share a huge capacity storage system. Such computersystems are currently widespread.

An advantage of such a computer system is an outstanding extendability:storage resources and computer resources can be easily added, deleted,or replaced at a later occasion. For a storage system that connects to aSAN, a storage system including RAID (Redundant Array of IndependentDisk) structured storage apparatuses are commonly used.

A fibre channel switch included in the SAN provides a zoning function. Azone is a unit of logical separation of a fibre channel network. Ascheme of this fibre channel zoning configures a zone with a group ofnetwork interfaces.

The network interfaces registered in a zone do not accept data transferto and from network interfaces which are not registered in the zone. Inother words, data transfer is available only among the networkinterfaces registered in the zone. The fibre channel switch can manageinformation on equipment connected to the SAN fabric, update thestatuses in response to a log-in of new equipment or a log-out, andrespond to a query about connection status.

PTL 1 in the citation list below discloses a system that connects avirtual storage system to a different external storage system havingstorage areas to provide a host computer with a storage area in thedifferent storage system to be used as a virtual storage area in thevirtual storage system; the technique is called external storageattachment technique.

PTL 2 discloses a storage system that transfers information in a logicalunit (volume) in a migration source storage system so as to match thesettings on a migration destination storage system to set configurationcontrol information.

PTL 3 discloses a technique that assigns a global LDEV number common toa plurality of storage systems in addition to a local LDEV number withina storage system. PTL 4 discloses a thin provisioning technique thatprohibits allocation of storage capacity to unwritten data areas toreduce redundancy in the storage capacity.

CITATION LIST Patent Literature

[PTL 1]

JP 2005-11277 A

[PTL 2]

JP 2008-176627 A

[PTL 3]

JP 2008-40571 A

[PTL 4]

U.S. Pat. No. 7,130,960

SUMMARY OF INVENTION Technical Problem

If system performance required for a storage system enlarges to exceedthe performance of a single storage system, it is necessary to use aplurality of storage systems as a resource for expansion of the systemperformance and reduction in management costs. For a plurality ofstorage systems to provide a host computer with services as a singlestorage system, it is necessary that the host computer can recognize theplurality of storage systems as a single storage system and alsouniquely locate the volumes in the plurality of storage systems.

The method disclosed in PTL 1 can increase the capacity of a storagesystem using an external storage system. However, in accessing theattached storage system, resources such as ports, CPUs, and cachememories in the original storage system are used all the time, so thatperformance cannot be expanded.

The method disclosed in PTL 2 can migrate a volume between storagesystems connected to a host computer. However, the administrator isrequired to manage the connection among the host computer and thestorage systems independently from volume allocation.

The method disclosed in PTL 3 can prevent LDEV numbers from coincidingwith each other in migration of a volume between storage systems.However, a typical host computer refers to information on the storagesystems in addition to the volume number to locate a volume. For thisreason, if volume migration is executed on-line, the information on thestorage system to which the volume belongs is changed, so that thedriver of the host computer is affected.

Accordingly, desired is a technique that a plurality of storage systemsappropriately provide a host computer with services as one storagesystem.

Solution to Problem

An aspect of the present invention is an information storage systemcomprising a plurality of storage systems connected to be able tocommunicate. Each of the plurality of storage systems includes assigneddefault storage system identification information which is the same tothe plurality of storage systems, common volume identificationinformation for uniquely identifying a volume provided by the pluralityof storage systems to a first host computer among the plurality ofstorage systems, and a controller configured to return the defaultstorage system identification information to the first host computer inresponse to a request from the first host computer and to process a reador write request to the volume accompanying the common volumeidentification information from the first host computer.

Advantageous Effects of Invention

According to an aspect of this invention, a plurality of storage systemscan appropriately provide a host computer with services as a storagesystem. Other problems, configurations, and effects of this inventionwill be clarified in the following explanations on a preferredembodiment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram of an overall computer system in anembodiment of this invention.

FIG. 2 is a diagram exemplifying a hardware configuration of amanagement computer in the embodiment.

FIG. 3 is a diagram exemplifying a hardware configuration of a storagesystem in the embodiment.

FIG. 4 is a diagram exemplifying a hardware configuration of a hostcomputer in the embodiment.

FIG. 5 is a diagram exemplifying a hardware configuration of aconnection apparatus in the embodiment.

FIG. 6 is a diagram exemplifying a volume configuration of anon-volatile storage apparatus and stored information in the storagesystem in the embodiment.

FIG. 7 is a drawing exemplifying information stored in a non-volatilestorage apparatus in a management computer in the embodiment.

FIG. 8 is a drawing exemplifying information stored in a managementinformation storage part in a non-volatile storage apparatus in astorage system in the embodiment.

FIG. 9 is a drawing exemplifying information stored in a non-volatilestorage apparatus in a host computer in the embodiment.

FIG. 10 is a drawing exemplifying information stored in a non-volatilestorage apparatus in a connection apparatus in the embodiment.

FIG. 11 is a drawing illustrating a configuration example of a storagesystem management table in a management computer in the embodiment.

FIG. 12 is a drawing illustrating a configuration example of a storagesystem port management table in a management computer in the embodiment.

FIG. 13 is a drawing illustrating a configuration example of a storagesystem pool management table in a management computer in the embodiment.

FIG. 14 is a drawing illustrating a configuration example of a storagesystem usage management table in a management computer in theembodiment.

FIG. 15 is a drawing illustrating a configuration example of a virtualstorage system volume management table in a management computer in theembodiment.

FIG. 16 is a drawing illustrating a configuration example of aconnection apparatus management table in a management computer in theembodiment.

FIG. 17 is a drawing illustrating a configuration example of a hostcomputer management table in a management computer in the embodiment.

FIG. 18 is a drawing illustrating a configuration example of aconnectivity-from-host management table in a management computer in theembodiment.

FIG. 19 is a drawing illustrating a configuration example of aconnectivity-between-storages management table in a management computerin the embodiment.

FIG. 20 is a drawing illustrating a configuration example of a defaultvirtual value management table in a management computer in theembodiment.

FIG. 21 is a drawing illustrating a configuration example of a storagesystem vendor name management table in a storage system in theembodiment.

FIG. 22 is a drawing illustrating a configuration example of a storagesystem model name management table in a storage system in theembodiment.

FIG. 23 is a drawing illustrating a configuration example of a storagesystem serial number management table in a storage system in theembodiment.

FIG. 24 is a drawing illustrating a configuration example of a storagesystem port management table in a storage system in the embodiment.

FIG. 25 is a drawing illustrating a configuration example of a volumemanagement table in a storage system in the embodiment.

FIG. 26 is a drawing illustrating a configuration example of a thinprovisioning pool management table in a storage system in theembodiment.

FIG. 27 is a drawing illustrating a configuration example of a thinprovisioning volume management table in a storage system in theembodiment.

FIG. 28 is a drawing illustrating a configuration example of a mediamanagement table in a storage system in the embodiment.

FIG. 29 is a drawing illustrating a configuration example of amanagement communication I/F address management table in a storagesystem in the embodiment.

FIG. 30 is a drawing illustrating a configuration example of a connectedstorage system's volume management table in a host computer in theembodiment.

FIG. 31 is a drawing illustrating a configuration example of amanagement communication I/F address management table in a host computerin the embodiment.

FIG. 32 is a drawing illustrating a configuration example of a connectedequipment management table in a connection apparatus in the embodiment.

FIG. 33 is a drawing illustrating a configuration example of a zoneconfiguration management table in a connection apparatus in theembodiment.

FIG. 34 is a drawing illustrating a configuration example of amanagement communication I/F address management table in a connectionapparatus in the embodiment.

FIG. 35 is a drawing illustrating a flow of adding a host computer in acomputer system in the embodiment.

FIG. 36 is a drawing illustrating a flow of adding a storage system in acomputer system in the embodiment.

FIG. 37 is a drawing illustrating a flow of deleting a storage system ina computer system in the embodiment.

FIG. 38 is a drawing illustrating a flow of creating a normal volume ina computer system in the embodiment.

FIG. 39 is a drawing illustrating a flow of creating a thin provisioningpool in a computer system in the embodiment.

FIG. 40 is a drawing illustrating a flow of creating a thin provisioningvolume in a computer system in the embodiment.

FIG. 41 is a drawing illustrating a flow of setting a port to a volumein a computer system in the embodiment.

FIG. 42 is a drawing illustrating a flow of setting an alternate path toa volume in a computer system in the embodiment.

FIG. 43 is a drawing illustrating a flow of processing an I/O requestfrom a host computer in a computer system in the embodiment.

FIG. 44 is a drawing illustrating a flow of leveling resources in acomputer system in the embodiment.

FIG. 45 is a drawing illustrating a flow of adjusting the capacity of athin provisioning pool in a computer system in the embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of this invention will be described withreference to the accompanying drawings. For clarity of explanation, thefollowing descriptions and the accompanying drawings contain omissionsand simplifications as appropriate. Throughout the drawings, likecomponents are denoted by like reference signs and their repetitiveexplanation is omitted for clarity of explanation, if not necessary.

This embodiment describes a configuration that enables a plurality ofstorage system to provide host computers with services as one storagesystem. The system in this embodiment assigns the same storage systemidentification information (default identifier) to a plurality ofstorage system. Moreover, it assigns volume identification informationunique within the plurality of storage systems to a volume.

A host computer locates a volume using the assigned storage systemidentification information and the volume identification information.For example, even if a volume is migrated from a storage system toanother while the system is in operation, the host computer can read orwrite the volume in the destination storage system using the storagesystem identification information and the volume identificationinformation.

FIG. 1 is a diagram for illustrating an example of an overallconfiguration of a computer system in an embodiment of this invention.As illustrated in this diagram, the computer system comprises amanagement computer 1, a plurality of (three in the example of FIG. 1)storage systems 2A to 2C, one or more (two in the example of FIG. 1)host computers 3A and 3B, and three connection apparatuses 4 to 6.

Hereinafter, storage system(s) 2 indicates arbitrary storage system(s)in the computer system and host computer(s) 3 indicates arbitrary hostcomputer(s) in the computer system.

The connection apparatus 4 transfers data I/O requests (requests fordata input or output) from host computers 3 to storage systems 2. Theconnection apparatus 5 transfers data I/O requests between storagesystems 2. The connection apparatus 6 transfers requests for managementcommunication from the management computer 1 to the storage systems 2,the host computers 3, and the connection apparatuses 4 and 5.

This computer system configures a SAN (Storage Area Network) between thehost computers 3 and the storage systems 2 with the connection apparatus4, but the host computers 3 may be directly connected to the storagesystems 2.

This computer system configures a SAN among the storage systems 2 withthe connection apparatus 5, but the storage systems 2 may be directlyconnected to one another. The connection apparatus 6 provides aconfiguration where for the management computer 1 can connect to theoverall computer system via an IP network, but the constituents of thesystem may be connected directly from the management computer 1.

The networks including the connection apparatuses 4 and 5 may benetworks provided by physically the same apparatus but being logicallyindependent. The networks including the connection apparatuses 4 and 5may be IP networks configured with iSCSI (Internet Small Computer SystemInterface) or may be logically independent networks provided by the sameapparatus providing the IP network provided by the connection apparatus6. Moreover, the networks including the connection apparatuses 4, 5, and6 may be included in a network configured with FCoE (Fibre Channel overEthernet) and provided by the same apparatus.

FIG. 2 illustrates an example of a hardware configuration of themanagement computer 1. The management computer 1 is a computercomprising a cache memory 11, a non-volatile storage apparatus 12, aprocessor 13, a program memory 14, a management communication I/F 16, aninternal bus 17, an image output apparatus 18, an input apparatus 19.The non-volatile storage apparatus 12 may be an external storageapparatus connected via a network.

The management computer 1 loads software such as an operating system(OS) and application programs stored in the non-volatile storageapparatus 12 to the program memory 14; the processor 13 retrieves themfrom the program memory 14 and executes them to provide predeterminedfunctions. The processor 13 may include a plurality of chips or aplurality of packages. The same applies to the other apparatuses(including the storage systems 2).

The management computer 1 temporarily stores frequently used data in thecache memory 11 to enhance the processing speed. The management computer1 includes an input apparatus 19 such as a keyboard, a mouse or both andan image output apparatus 18 such as a monitor. The input apparatus 19accepts inputs from the administrator (user) and the image outputapparatus 18 outputs information instructed by the processor 13. Themanagement computer 1 further includes a management communication IF 16for connecting to the connection apparatus 6.

In the configuration example of FIG. 1, a management system isconfigured with the management computer 1, but the management system maybe configured with a plurality of computers: one may be a computer fordisplay and the other plurality of computers may perform jobs equivalentto those in the management computer for speedy management and higherreliability.

FIG. 3 illustrates an example of hardware configuration of a storagesystem 2. The storage system 2 comprises a cache memory 21, anon-volatile storage apparatus 22, a processor 23, a program memory 24,a data I/O communication I/F 25, a management communication IF 26, aninternal bus 27, an image output apparatus 28, and an input apparatus29.

The storage system 2 loads software such as an OS and applicationprograms stored in the non-volatile storage apparatus 22 to the programmemory 24; the processor 23 retrieves them from the program memory 24and executes them to provide predetermined functions. The processor 23functions as a controller of the storage system 2. The storage system 2stores frequently used data in the cache memory 21 to enhance theprocessing speed.

The storage system 2 includes an input apparatus 29 such as a keyboard,a mouse or both and an image output apparatus 28 such as a monitor. Theinput apparatus 29 accepts inputs from the administrator (user) and theimage output apparatus 28 outputs information instructed by theprocessor 23. The storage system 2 includes one or more data I/Ocommunication I/Fs 25 for connecting to the connection apparatuses 4 and5 and a management communication I/F 26 for connecting to the connectionapparatus 6. It should be noted that the data I/O communication I/Fs 25and the management communication I/F 26 may be provided by physicallythe same apparatus.

For simplicity, FIG. 1 shows three storage systems 2 but the system maycomprise two or more than three storage systems 2. A port ID unique inthe computer system is assigned to the data I/O communication IF 25, anda plurality of virtual port IDs can be assigned using NPIV (N_Port IDVirtualization) or any other virtualization scheme.

The data I/O communication I/F 25 supports both of a target mode forreceiving a read or write request from a host computer 3 and aninitiator mode for sending a read or write request to a differentstorage system 2. The storage system 2 may have physically differentdata I/O communication I/Fs 25 for those modes, but a physically singleI/F may logically satisfy the both functions.

FIG. 4 illustrates an example of a hardware configuration of a hostcomputer 3. The host computer 3 is a computer comprising a cache memory31, a non-volatile storage apparatus 32, a processor 33, a programmemory 34, a data I/O communication I/F 35, a management communicationI/F 36, an internal bus 37, an image output apparatus 38, and an inputapparatus 39.

The host computer 3 loads software such as an OS and applicationprograms stored in the non-volatile storage apparatus 32 to the programmemory 34; the processor 33 retrieves them from the program memory 34and executes them to provide predetermined functions. The processor 3stores frequently used data in the cache memory 31 to enhance theprocessing speed.

The host computer 3 includes an input apparatus 39 such as a keyboard, amouse or both and an image output apparatus 38 such as a monitor. Theinput apparatus 39 accepts inputs from the administrator (user) and theimage output apparatus 38 outputs information instructed by theprocessor 33. The host computer 3 includes one or more data I/Ocommunication I/Fs 35 for connecting to the connection apparatuses 4 and5 and a management communication I/F 36 for connecting to the connectionapparatus 6. The data I/O communication I/Fs 35 and the managementcommunication I/F 36 may be provided by physically the same apparatus.

For simplicity, FIG. 1 shows two host computers 3 but the system maycomprise any number of host computers 3. A port ID unique in thecomputer system is assigned to a data I/O communication I/F 35, and aplurality of virtual port IDs can be assigned using NPIV or any othervirtualization scheme.

FIG. 5 illustrates an example of a hardware configuration of theconnection apparatus 4. The connection apparatus 4 comprises a cachememory 41, a non-volatile storage apparatus 42, a processor 43, aprogram memory 44, a data I/O communication I/F 45, a managementcommunication I/F 46, an internal bus 47, and link lamps 48.

The connection apparatus 4 loads software such as an OS and applicationprograms stored in the non-volatile storage apparatus 42 to the programmemory 44; the processor 43 retrieves them from the program memory 44and executes them to provide predetermined functions. The connectionapparatus 4 stores frequently used data in the cache memory 41 toenhance the processing speed. The connection apparatus 4 includes linklamps 48 having light-emitting elements such as LEDs to visualize thestatuses of logical connections in the data I/O communication I/F 45.The connection apparatuses 5 and 6 have the same configuration as theconnection apparatus 4.

FIG. 6 illustrates a configuration of a non-volatile storage apparatus22 in a storage system 2. The non-volatile storage apparatus 22 includesa storage system management information storage part 221 and differenttypes of media 222A to 222C equipped with non-volatile storage media. Inthis description, a group composed of one or more media drives isreferred to as a medium. A medium or media 222 indicate an arbitrarymedium or arbitrary media.

In the example of FIG. 6, a SSD (Solid State Drive) medium 222A whichutilizes a flash memory of a semiconductor memory, a SAS (SerialAttached SCSI) medium 222B which includes a SAS interface, and a SATA(Serial Advanced Technology Attachment) medium 222C which includes aSATA interface are exemplified.

The storage system 2 provides one or more volumes (real volumes) 2221which are formed of real storage areas provided by media 222 andreadable and writable from a host computer 3 or a thin provisioning pool223. A volume 2221 may be provided by a single taype of medium 222 ormay be provided from a RAID (Redundant Arrays of Inexpensive Disks)configured by a plurality of types of media 222. Hereinafter, an examplein which each volume 2221 is formed by using a single taype of medium222 will be described.

In a thin provisioning pool 223, a volume 2221 selected out of volumes2221 of the media 222 by the administrator (user) is divided into aplurality of pages 2231. The thin provisioning pool 223 is managed inunits of page. A thin provisioning volume 224 is a virtual volumeprovided to a host computer 3 and the capacity is virtualized. Everytime a host computer 3 writes data to its thin provisioning volume 224to cause a need of a data storage area, the storage system 2 allocates apage 2231 to the thin provisioning volume 224.

Thin provisioning can make the capacity of a thin provisioning volume224 recognized by a host computer 3 larger than the real capacityallocated to the thin provisioning volume 224 (the total capacity of allof the pages) and can make the real capacity to achieve the capacityallocated to the host computer 3 smaller than the allocated capacity.

FIG. 7 illustrates information stored in the non-volatile storageapparatus 12 in the management computer 1. A storage system managementprogram 121 checks the statuses of the storage systems 2 in the computersystem and sets configuration information on them through communicationvia the connection apparatus 6 connected from the managementcommunication I/F 16. A connection apparatus management program 122checks the statuses of the connection apparatuses 4 and 5 in thecomputer system and sets configuration information on them throughcommunication via the connection apparatus 6 connected from themanagement communication I/F 16.

A host computer management program 123 checks the statuses of the hostcomputers 3 in the computer system and specifies configurationinformation on them through communication with agents 322 (refer to FIG.9) in the host computers 3 via the connection apparatus 6 connected fromthe management communication I/F 16. An operation management program 124designs volume allocation and executes other jobs with reference totables in the non-volatile storage apparatus 12 in the managementcomputer 1. The operation management program 124 further managesoperations in the computer system in cooperation with various programsand provides the administrator with a user interface. An operatingsystem 125 is a platform for executing the various programs and formanaging various tables.

The programs are executed by the processor 13 to perform predeterminedjobs using the storage apparatus and the management communication I/F16. Accordingly, in this embodiment, the explanations having thesubjects of program may be explanations having the subjects ofprocessor. The jobs executed by a program are the jobs executed by thecomputer or the computer system on which the program is running.

The processor 13 works in accordance with a program to work as anoperation part (means) to implement a predetermined function. Forexample, the processor 13 works in accordance with the storage systemmanagement program 121 to function as a storage manager and works inaccordance with the connection apparatus management program 122 tofunctions as a connection apparatus manager. The same apply to the otherprograms.

Moreover, the processor 13 also works as operation parts to implementthe respective jobs executed by the programs. The management computer 1including the processor 13 and the programs is an apparatus includingthese operation parts. The explanations on the relationship between theprograms and the processor and the relationship between the programs andthe processor, and the apparatus including them apply to the otherapparatuses and systems, namely, each host computer 3, the connectionapparatuses 4 to 6, and each storage system 2.

The non-volatile storage apparatus 12 further stores a storage systemmanagement table 100, a storage system port management table 110, astorage system pool management table 120, a storage system usagemanagement table 130, a virtual storage system volume management table140, a connection apparatus management table 150, a host computermanagement table 160, a connectivity-from-host management table 170, aconnectivity-between-storages management table 180, and a defaultvirtual value management table 190. Details on these tables will bedescribed later.

In this embodiment, the information used by the management computer 1does not depend on the data structure but may be expressed in any datastructure. For example, a data structure appropriately selected fromtable, list, database, and queue can store the information. Informationis stored in a pertinent data storage area in a data storage apparatus.The same applies to the other apparatuses (including the storagesystems).

FIG. 8 illustrates information stored in the storage system managementinformation storage part 221 in a storage system 2. A data I/O program2211 communicates with host computers 3 in the computer system via theconnection apparatus 4 connected from the data I/O communication I/F 25,sends and receives data for the volume 2221 and the thin provisioningvolume 224 and writes to them.

A pool management program 2212 manages pages 2231 in a thin provisioningpool 223, volumes 2221 as pool volumes, and allocation of the pages 2231to thin provisioning volumes 224. A volume management program 2213manages the volumes 2221 and the thin provisioning volumes 224. Anoperation management program 2214 manages operations in the storagesystem 2 in cooperation with various programs. An operating system 2215is a platform for executing the various programs and for managingvarious tables.

The storage system management information storing part 221 furtherstores a storage system vendor name management table 200, a storagesystem model name management table 210, a storage system serial numbermanagement table 220, a storage system port management table 230, avolume management table 240, a thin provisioning pool management table250, a thin provisioning volume management table 260, a media managementtable 270, and a management communication I/F address management table280. Details on these tables will be described later.

FIG. 9 illustrates information stored in the non-volatile storageapparatus 32 in a host computer 3. Applications 321 are programsrequired for the host computer 3 to provide the functions or services.An agent 322 checks the status of the host computer 3 and specifiesconfiguration information thereon through communication with the hostcomputer management program 123 in the management computer 1. Anoperating system 323 is a platform for executing various programs in theapplications 321 and for managing various tables. The non-volatilestorage apparatus 32 further stores a connected storage system's volumemanagement table 300 and a management communication I/F addressmanagement table 310. Details on these tables will be described later.

FIG. 10 illustrates information stored in the non-volatile storageapparatus 42 in the connection apparatus 4. A data I/O program 421receives I/O requests from computers and systems in the computer systemconnected to the data I/O communication IF 45 and communicates with themwith reference to the tables in the non-volatile storage apparatus 42.

A management program 422 provides an interface for setting the values inthe tables in the non-volatile storage apparatus 42. An operating system423 is a platform for executing various programs and for managingvarious tables. The non-volatile storage apparatus 42 further stores aconnected equipment management table 400, a zone configurationmanagement table 410, and a management communication I/F addressmanagement table 420. Details on these tables will be described later.

FIG. 11 is a drawing illustrating a configuration example of a storagesystem management table 100 in the management computer 1 in thisembodiment. The storage system management table 100 has columns ofstorage system IDs 1001, where a storage system ID is an ID uniquelyassigned to a storage system 2 to manage it in the computer system,storage system vendor names 1002, storage system model names 1003 andstorage system serial numbers 1004. The storage system vendor name,storage system model name and storage system serial number are specifiedat shipment of the storage system.

These values are obtained by the management computer 1 from the storagesystems 2 via the connection apparatus 6 or directly inputted by theadministrator. In this embodiment, IDs, names, and numbers are used asinformation for identifying targets, but these nominal designations canbe replaced with one another.

The storage system management table 100 further has columns of defaultvirtual vendor names 1005, default virtual model names 1006 and defaultvirtual serial numbers 1007 which are used to respond to a request forinformation on connection ports or volumes issued by a host computer 3in a SCSI Inquiry. These columns store the values copied from thedefault virtual value management table 190 specified by theadministrator and the administrator can change the values. Theadministrator may specify these values individually.

The storage system management table 100 further has a column ofmanagement communication I/F addresses 1008 for managing the storagesystems 2. The values in this column are inputted by the administrator.

An entry in the storage system management table 100 is added when anadditional storage system 2 is installed in the computer system and theadministrator issues an instruction to add a storage system. An entry inthe storage system management table 100 is deleted when theadministrator issues an instruction to delete a storage system 2 toremove a storage system 2 and a series of processes are finished.

FIG. 12 is a drawing illustrating a configuration example of a storagesystem port management table 110 in the management computer 1 in thisembodiment. This table 110 manages the statuses of the data I/Ocommunication I/Fs 25 in association with the storage system IDs 1001 inthe storage system management table 100.

Usually, a plurality of data I/O communication I/Fs 25 are installed ina storage system and each data I/O communication I/F 25 is assigned aunique number in the storage system (a data I/O communication I/F number1102). These numbers are used in accessing a storage system utilizing aplurality of paths in accordance with an alternate path program(multipath program).

Use 1103 of a data I/O communication I/F 25 is either for an access froma host or for an access between storage systems (for migration), forexample. In an access between storage systems, if each port is eitherfor targets only or for initiators only, the storage system managementtable 100 manages the modes of the ports. In the column of the use 1103,the administrator (user) inputs values designed at the construction ofthe system.

A data I/O communication IF number 1102 is a unique number in a storagesystem, but in the case where a plurality of storage systems 2 aremanaged as a single storage system, duplicate data I/O communication I/Fnumbers 1102 may be created.

For this reason, in the computer system in this embodiment, themanagement computer 1 assigns a unique virtual number (virtual data I/Ocommunication I/F number 1104) to a data I/O communication IF 25 in astorage system 2. The management computer 1 notifies the storage system2 of this number via the connection apparatus 6.

The storage system 2 stores the number in virtual data I/O communicationI/F number 2302 in its storage system port management table 230 and usesthe number in subsequent I/Os of the storage system 2 with the hostcomputers 3 and other processes. To the data I/O communication I/F 25, aport ID is assigned to be used to locate the source or the destinationof communication through the connection apparatus 4 or 5.

The port ID may be assigned at shipment of hardware or changed with atool afterwards. Furthermore, a data I/O communication I/F can beassigned a plurality of virtual port IDs and the storage system portmanagement table 230 manages the assigned values in the fields for portID 1105 and virtual port ID 1106.

Entries in the storage system port management table 110 are added ordeleted in synchronization with the entries in the storage systemmanagement table 100. In the following descriptions, the term of port IDmeans either port ID 1105 (also referred to as real port ID in contrastto virtual port ID) or virtual port ID 1106, if no specific designation.In managing ports, the real port IDs and the virtual port IDs can betreated on the same plane.

FIG. 13 is a drawing illustrating a configuration example of a storagesystem pool management table 120 in the management computer 1 in thisembodiment. This table 120 manages thin provisioning pools 223 in thestorage systems in the computer system and has columns of pool names1201, where a pool name is a common name shred by one or more storagesystems; total capacities 1202, where the total capacity provided by theone or more storage systems is stored; and amount of usage 1203 of thepool.

Furthermore, the storage system pool management table 120 stores thevalues obtained by copying the storage system IDs 1001 of the individualstorage systems that constitute the pool from the storage systemmanagement table 100 in the fields of 1204, and has fields of capacity1205A, amount of usage 1205B, and IOPS (Input Output Per Second) 1206Afor each of the storage systems.

Still further, the storage system pool management table 120 containscapacity thresholds 1205C and performance thresholds 1206B, which arethe threshold values to perform adjustment if the amounts of usage andthe IOPS, respectively, exceed them in the individual storage systems 2.In addition, the table contains constituent volume IDs 1207A for thevolumes that constitute the pool, and capacities 1207B and amounts ofusage 1207C for the individual constituent volumes.

An entry in the storage system pool management table 120 is added whenthe administrator issues an instruction to create a thin provisioningpool 223 and deleted when the administrator issues an instruction todelete a thin provisioning pool 223. An entry of the constituent volumeID 1207A associated with a storage system ID 1204 are added or deletedresponsive to addition or deletion of the volume.

The values of the capacity threshold 1205C and the performance threshold1206B are specified by the administrator. To obtain the values of theamount of usage 1205B, the IOPS 1206A, and the amount of usage 1207C,the management computer 1 periodically makes an inquiry to the storagesystem 2 via the connection apparatus 6 and stores obtained values fromthe storage system 2 to the fields.

FIG. 14 is a drawing illustrating a configuration example of a storagesystem usage management table 130 in the management computer 1 in thisembodiment. The storage system usage management table 130 manages theusage of each storage system 2 and has a column of storage system IDs1301 corresponding to the storage system IDs 1001 in the storage systemmanagement table 100.

The storage system usage management table 130 further has columns forstoring values of the capacity 1302, the capacity threshold 1303, andthe amount of usage 1304 of the storage system identified by eachstorage system ID 1301. Moreover, it includes values of the media type1306, the RAID structure 1307, the capacity 1308, and the amount ofusage 1309 for each of the media IDs 1305 in each storage system. Toobtain the other values associated with the value of each storage systemID 1301, the management computer 1 periodically makes an inquiry to eachstorage system 2 via the connection apparatus 6 and stores obtainedvalues to the fields.

FIG. 15 is a drawing illustrating a configuration example of a virtualstorage system volume management table 140 in the management computer 1in this embodiment to manage a plurality of volumes existing in thecomputer system with unique numbers assigned. A virtual volume number1401 is assigned to each virtual volume and the information on the otheritems is managed in association with the virtual volume number.

A capacity 1402 indicates the capacity of a virtual volume; an amount ofusage 1403 indicates the amount of usage of a virtual volume; and avolume type 1404 indicates which type of volume a virtual volume is, anormal volume, a thin provisioning volume, or pool volume.

The virtual storage system volume management table 140 further includescolumns of IDs 1405 of the storage systems where the volumes actuallyexist, volume IDs 1406 which are identification information for uniquelyidentifying volumes in the storage systems (only), media IDs 1407 foridentifying RAID groups in the storage systems 2, virtual port numbers1408A, and alternate virtual port numbers 1408B.

A value of the virtual volume ID 1401 is assigned at creation of avolume and is a common number in this computer system (all of thestorage systems 2) and identification information for uniquelyidentifying the volume in the computer system. Values of the capacity1402 and the volume type 1404 are specified by the administrator atcreation of the volume. Depending on the situation, a value of the mediaID 1407 is specified and in accordance with the specification, aninstruction to create a volume is sent to the storage system 2.

Values of the virtual port number 1408A and the alternate virtual portnumber 1408B are set for the administrator to specify from which dataI/O communication I/F 25 in a storage system 2 in the computer systemthe volume is to be accessed. The values of the virtual data I/Ocommunication IF numbers are assigned to the values of the virtual portnumber 1408A and the alternate virtual port number 1408B.

FIG. 16 is a drawing illustrating a configuration example of aconnection apparatus management table 150 in the management computer 1in this embodiment. The table 150 has columns of connection apparatusIDs 1501, apparatus names 1502 of the connection apparatuses, managementcommunication I/F addresses 1503 for the connection apparatuses, and use1504 of the connection apparatuses. A connection apparatus for hostsconnects host computers to storage systems and a connection apparatusfor migration connects storage systems. Values in each column areinputted by the administrator. The management computer 1 refers to thevalues for management communication with the connection apparatus 4, 5,or 6.

FIG. 17 is a drawing illustrating a configuration example of a hostcomputer management table 160 in the management computer 1 in thisembodiment. This table 160 has columns of host IDs 1601; host IPs 1602,which are the addresses of the management communication I/Fs in the hostcomputers 3; and host-side port IDs 1603, which are the port IDs of theaddresses of the data I/O communication I/Fs.

Values in these columns are inputted by the administrator and referredto when management communication to a host computer 3 is necessary. Themanagement computer 1 may ask the agent 322 or the operating system 323in a host computer 3 for the host-side port ID 1603 after the value ofthe host IP 1602 is inputted.

FIG. 18 is a drawing illustrating a configuration example of aconnectivity-from-host management table 170 in the management computer 1in this embodiment to manage the storage systems 2 connectable from thedata I/O communication I/Fs 35 in the host computers 3. This table 170has columns of connection apparatus connectivity 1702, connectable portIDs 1703, and connectivity 1704.

A connection apparatus connectivity 1702 stores a check status on theconnectivity between the port ID 1701 of the data I/O communication IF35 in a host computer and the connection apparatus 4. A connectivity1704 stores a check status on the connectivity between the port ID 1701of the data I/O communication I/F 35 in a host computer and aconnectable port ID 1703.

The management computer 1 communicates with the connection apparatus 4via the connection apparatus 6, inquires about the connectivity of atarget host computer 3, and stores obtained information to theconnection apparatus connectivity 1702.

Connectable port IDs 1703 store a copied list of the port IDs 1105 orthe virtual port IDs 1106 of the entries containing the value “for host”in the use 1103 in the storage system management table 100. Themanagement computer 1 notifies each storage system 2 of the port ID 1701of a host computer 3, instructs the connection apparatus 4 to querywhether the storage system 2 can connect to the port ID, and obtains thestatus.

The check method may inform the agent 322 in each host computer 3 of theconnectable port IDs 1703, and instructs the connection apparatus 4 toquery whether connections are available or not to obtain the statuses,instead of obtaining the statuses via the storage systems 2.

A connection apparatus connectivity 1702 is a field for checking whetherthe host computer 3 of an entry is connected to the connection apparatus4 which is connectable to the storage systems 2, and the managementcomputer 1 outputs an error if the host computer 3 is not connected. Theconnectivity 1704 is used to limit an access port range for provisioningor migration with an assumption that connection through some port mightbe disabled.

FIG. 19 is a drawing illustrating a configuration example of aconnectivity-between-storages management table 180 in the managementcomputer 1 in this embodiment to manage connection statuses of the dataI/O communication I/Fs between storage systems 2. The table 180 of FIG.19 shows an example of a connectivity-between-storages management tablefrom a certain port. The table stores information on the connectivitybetween the certain port and a port of each entry. For example, thetable 180 is a table for a port of in a storage system having thestorage system ID of 3.

The connectivity-between-storages management table 180 has columns ofstorage system IDs 1801, port IDs 1802 of the data I/O communicationI/Fs 25 in the storage systems 2 corresponding to the IDs, andconnectivity 1803.

To check the connectivity 1803 between (ports of) storage systems, themanagement computer 1 notifies storage systems 2 of their port IDs 1105or virtual port IDs 1106 whose entries contain the value of “formigration” in the use 1103 in the storage system management table 100and instructs each of the storage systems 2 to query the connectionapparatus 5 about whether each of the ports (port IDs 1105 or virtualport IDs 1106) can connect from some port in a different storage system.The management computer 1 obtains information on the status(connectivity) from each storage system 2.

FIG. 20 is a drawing illustrating a configuration example of a defaultvalue management table 190 in the management computer 1 in thisembodiment to manage default values for a storage system 2 in thecomputer system to notify a host computer 3. All of the values fordefault virtual vendor names 1901, default virtual model names 1902, anddefault virtual serial numbers 1903 are inputted by the administrator atthe initial setting.

FIG. 21 is a drawing illustrating a configuration example of a storagesystem vendor name management table 200 in a storage system 2 in thisembodiment. The storage system vendor name management table 200 stores avalue to be copied to the virtual vendor name 2406A in the volumemanagement table 240, which is a value to be returned to a host computer3. When installing a storage system 2 into the computer system, theoperation management program 2214 stores a default virtual vendor name1901 transmitted from the management computer 1 via the connectionapparatus 6 to this table.

FIG. 22 is a drawing illustrating a configuration example of a storagesystem model name management table 210 in a storage system 2 in thisembodiment. The storage system model name management table 210 stores avalue to be copied to the virtual model name 2406B in the volumemanagement table 240, which is a value to be returned to a host computer3. When installing a storage system 2 into the computer system, theoperation management program 2214 stores a default virtual model name1902 transmitted from the management computer 1 via the connectionapparatus 6 to this table.

FIG. 23 is a drawing illustrating a configuration example of a storagesystem serial number management table 220 in a storage system 2 in thisembodiment. The storage system serial number management table 220 storesa value to be copied to the virtual serial number 2406C in the volumemanagement table 240, which is a value to be returned to a host computer3. When introducing a storage system 2 into the computer system, theoperation management program 2214 stores a default virtual serial number1903 transmitted from the management computer 1 via the connectionapparatus 6 to this table.

FIG. 24 is a drawing illustrating a configuration example of a storagesystem port management table 230 in a storage system 2 in thisembodiment. The table 230 is for managing data I/O communication I/Fs 25in a storage system 2 and has columns of data I/O communication I/Fnumbers 2301, virtual data I/O communication I/F numbers 2302, use 2303,port IDs 2304, and virtual port IDs 2305.

A data I/O communication I/F number 2301 holds a hardware-specificvalue, and in association with it, a unique virtual data I/Ocommunication I/F number 2302 in the computer system is assigned. Themanagement computer 1 creates a value unique to the computer systembased on the virtual data I/O communication I/F number 1104 in thestorage system port management table 110 and transmits it to the storagesystem 2 via the connection apparatus 6 and the operation managementprogram 2214 stores the value to the table.

Use 2303 stores a value indicating either for hosts or for migration,which is specified by the administrator. A port ID 2304 stores ahardware-specific value provided to the data I/O communication I/F. Avirtual port ID 2305 is an ID virtually assigned to the port ID and itis different from the hardware-specific port ID.

FIG. 25 is a drawing illustrating a configuration example of a volumemanagement table 240 in a storage system 2 in this embodiment. The table240 is for managing the configuration and conditions of volumes in thestorage system 2. Each entry is uniquely identified by the value of thevolume ID 2401.

A capacity 2402 indicates the capacity of the volume. A type 2403 storesinformation indicating that the volume is a normal volume, a thinprovisioning volume, or a thin provisioning pool volume. A media ID 2404stores an ID of the media for which the volume is created. A virtualvolume number 2405 stores a number uniquely determined in the system andassigned by the management computer 1 at the creation of the volume.

Values of a virtual vendor name 2406A, a virtual model name 2406B, avirtual serial number 2406C, a virtual port number 2407A, and analternate virtual port number 2407B are used to respond to queries on avolume or a port from a host computer 3. A port number 2408A and analternate port number 2408B store the numbers of a port and an alternateport used for actual I/Os. Cache allowability 2409 stores a valueindicating the allowability of cache to an I/O request from a hostcomputer.

An entry of the table is created in response to a request for creating avolume from the management computer 1. To the volume ID 2401, thestorage system 2 assigns a unique value in creating a new volume. Thecapacity 2402 and the type 2403 store values specified by theadministrator. If the media ID 2404 is specified, the storage system 2creates a volume for the specified media. If it is not specified, thestorage system 2 creates a volume for arbitrary media and stores the IDof the media.

The column of virtual volume numbers 2405 store values assigned by themanagement computer 1 to uniquely identify virtual volumes in thecomputer system. The virtual volume numbers 2405 informed of by themanagement computer 1 is identification information shared in thecomputer system.

The columns of virtual vendor names 2406A, virtual model names 2406B,and virtual serial numbers 2406C store values of the default virtualvendor name 2002 in the storage system vendor name management table 200,the default virtual model name 2102 in the storage system model namemanagement table 210, and the default virtual serial number 2202 in thestorage system serial number management table 220, respectively. If theadministrator wants to take over the values for different storagesystems, those values may be stored.

A virtual port number 2407A and an alternate virtual port number 2407Bare specified by the administrator. The storage system 2 refers to thestorage system port management table 230 and if a virtual data I/Ocommunication IF number 2302 corresponding to the virtual port number2407A or the alternate virtual port number 2407B exists, it stores therelevant data I/O communication I/F number 2301 to the port number 2408Aor the alternate port number 2408B.

If the corresponding virtual data I/O communication I/F number 2302 doesnot exists, the storage system 2 stores the value of the data I/Ocommunication I/F 2301 in an entry containing the value “for migration”in the use 2303 to the port number 2408A or the alternate port number2408B. If both of the use 2303 of the port number 2408A and thealternate port number 2408B of the entry indicate “for host”, thestorage system 2 stores values indicating “allowable” in the fields forthe cache allowability 2409 of the entries. It stores values indicating“unallowable” otherwise.

FIG. 26 is a drawing illustrating a configuration example of a thinprovisioning pool management table 250 in a storage system 2 in thisembodiment. The table 250 is for managing the configurations of thinprovisioning pools 223 and has columns of pool IDs 2501, totalcapacities 2502, amounts of usage 2503, constituent volume IDs 2504,capacities 2505, amounts of usage 2506, page numbers 2507, and statuses2508.

A pool ID 2501 is a value uniquely determined among the storage systems2 and specified by the administrator at the creation of a pool by themanagement computer 1. A total capacity 2502 is a total amount of thecapacities of the constituent volumes 2505 associated with the pool ID.An amount of usage 2503 is a total amount of the amounts of usage of theconstituent volumes 2506.

A constituent volume ID 2504 stores a volume ID 2401 of the volumeselected for the pool from the volume management table 240. A capacity2505 stores a value copied from the capacity 2402 of the entrycorresponding to the selected volume ID 2401. An amount of usage 2506stores zero as the initial value.

A volume is divided into pages 2231 to allocate them to thinprovisioning volumes 224; accordingly, numbers individually assigned tothe plurality of pages are stored in page numbers 2507. A field forstatus 2508 stores a value indicating the status of allocation of thepage. If another page is needed for a thin provisioning volume becauseof a write request from a host computer 3, a page indicating a status2508 “unallocated” is allocated and the status 2508 of the page ischanged into “allocated”. Moreover, the size of the allocated page isadded to the amount of usage 2506.

FIG. 27 is a drawing illustrating a configuration example of a thinprovisioning volume management table 260 in a storage system 2 in thisembodiment. The thin provisioning volume management table 260 indicatespages 2231 to constitute a thin provisioning volume 224 and has columnsof volume IDs 2601, maximum capacities 2602, amounts of usage 2603, poolIDs 2604, constituent volume IDs 2605, and page numbers 2606.

In accordance with an instruction of the management computer 1 to createa volume, an entry is added to the volume management table 240. If thetype 2403 therein is “thin provisioning”, an entry is added to the thinprovisioning volume management table 260. A volume ID 2601 stores avalue copied from the volume ID 2401 in the volume management table 240.

A maximum capacity 2602 stores a value copied from the capacity 2402 inthe volume management table 240. The initial value of an amount of usage2603 is zero. Every time a new page allocated is needed because of awrite from a host computer 3, a page is allocated whose status 2508shows “unallocated” among the pages in association with the pool ID2604. The values of the constituent volume ID 2504 and the page number2507 are copied and stored to the constituent volume ID 2605 and thepage number 2606.

FIG. 28 is a drawing illustrating a configuration example of a mediamanagement table 270 in a storage system 2 in this embodiment. The mediamanagement table 270 manages the conditions of media 222 and has columnsof media IDs 2701, media types 2702, RAID structures 2703, capacities2704, and amounts of usage 2705.

To a media ID 2701, a unique value is assigned when a medium 222 isadded to a storage system 2. To a media type 2702, a value such as SSD,SAS, or SATA is inputted by the administrator in accordance with theadded media. A RAID structure 2703 stores a value the administratorinputs in accordance with the constructed RAID structure. A capacity2704 stores the size of the installed media inputted by theadministrator. The storage system 2 may scan every media and summarizethe capacities. An amount of usage 2705 contains the initial value ofzero and stores the amount of usage obtained by adding the amountallocated at the creation of the volume.

FIG. 29 is a drawing illustrating a configuration example of amanagement communication I/F address table 280 in a storage system 2 inthis embodiment. The table 260 stores the addresses 2801 of managementcommunication I/Fs 26. At the installation of a storage system 2 to thecomputer system, the administrator specifies the value.

FIG. 30 is a drawing illustrating a configuration example of a connectedstorage system's volume management table 300 in a host computer 3 inthis embodiment. This table 300 stores information on volumes which areallocated to a host computer 3 and readable or writable. This table hascolumns of IDs 3001, volume IDs 3002, system vendor names 3003, systemmodel names 3004, system serial numbers 3005, port IDs 3006, and dataI/O communication I/F numbers 3007.

An ID 3001 is an identifier uniquely assigned to each volume in a hostcomputer 3. A port ID 3006 is a port ID (virtual port ID or real portID) in the storage system 2 to access; the value may be input by theadministrator or may store the value of which the management computer 1notifies the agent 322. The operating system 323 in the host computer 3refers to the port ID 3006 to access the storage system 2.

The operating system 323 obtains a virtual volume number uniquelyidentifying the volume in the computer system from the managementcomputer 1 and stores it in the field for the volume ID 3002. Theoperating system 323 sends an information acquisition request to obtaininformation on the volume identified with the volume ID 3002 to (theport indicated by the value of the port ID 3006 of) the storage system 2via the connection apparatus 4.

The operating system 323 stores information obtained in response to thisrequest from the storage system 2 to the fields for the system vendorname 3003, the system model name 3004, the system serial number 3005,and the data I/O communication I/F number 3007. A data I/O communicationI/F number 3007 stores the value of the virtual data I/O communicationI/F number 1104 in the storage system 2 (the unique data I/Ocommunication I/F number in the computer system).

In this configuration, the system vendor name 3003, the system modelname 3004, the system serial number 3005 store default values (samevalues) 2002, 2102, and 2202, respectively, which are common to all ofthe storage systems 2. These values are storage identificationinformation common to (same to) all of the storage systems 2.

The operating system 323 and an alternate path program in the hostcomputer 3 locate a volume using identification information on volumesand identification information on the storage system to which the volumebelongs. If the identification information is changed in operation ofthe system, the host computer 3 cannot recognize that the volume is thesame one, so that it cannot access (read or write data) the volume.

For example, in this configuration, if any one of the system vendor name3003, the system model name 3004, and the system serial number 3005 ischanged, the host computer 3 identifies the volume as the one belongingto a different storage system and as a different volume (cannot identifyit as the same volume).

This system assigns virtual volume numbers, which are uniqueidentification information common to a plurality of the storage systems2, to the volumes provided by the plurality of storage systems 2.Moreover, each storage system 2 holds default storage identificationinformation (foregoing default values) same for the plurality of storagesystems in addition to identification information in the individualstorage systems 2. The host computer 3 is provided with the defaultstorage identification information for the volume information.

If the storage identification information and the volume identificationinformation are the same, the host computer 3 can normally accessvolumes in different storage systems. In other words, the host computer3 regards a plurality of storage systems 2 as a single storage systemand can access the volumes in the storage systems 2 without any trouble.

For example, a volume in the storage system 2A is migrated to thestorage system 2B, the host computer 3 can access the migrationdestination volume using the same volume identification information andthe same storage identification information. In addition, the hostcomputer 3 can read or write to a volume in the storage system 2A viaeither one of the port in the storage system 2A and the port in thestorage system 2B (the details of this method using an externalconnection technique will be described later).

In this configuration example, the common storage system identificationinformation includes the system vendor name 3003, the system model name3004, and the system serial number 3005, but may include only a part ofthese or additional different information. The information required fora host computer 3 to identify volumes are determined depending on thedesign and the common storage system identification information isdetermined in accordance with the design; typically, the informationincludes the system type name and the system serial number.

FIG. 31 is a drawing illustrating a configuration example of amanagement communication I/F address management table 310 in a hostcomputer 3 in this embodiment. The table 310 stores the address 3101 ofa management communication I/F 36. At the installation of a hostcomputer 3 to the computer system, the administrator specifies thevalue.

FIG. 32 is a drawing illustrating a configuration example of a connectedequipment management table 400 in each of the connection apparatuses 4,5, and 6 in this embodiment. The table 400 is a table for managingconnection statuses to the data I/O communication I/Fs 45 of each of theconnection apparatuses 4, 5, and 6 and has columns of connection numbers4001, port IDs 4002 and lamp statuses 4003.

A connection number 4001 is a number assigned to the hardware of a dataI/O communication I/F 45. Upon physical connection from some equipment,each of the connection apparatuses 4, 5, and 6 obtains the port IDassigned to the connected equipment and stores it in the port ID 4002. Avalue in the lamp status 4003 is set at ON if the equipment is connectedand its port ID is obtained; and is set at OFF otherwise. The managementprogram 422 in the connection apparatus monitors the lamp statuses 4003;if some lamp status is ON, it turns on the link lamp 48 connected to thedata I/O communication I/F 45, and if it is OFF, it turns off the linklamp 48.

FIG. 33 is a drawing illustrating a configuration example of a zoneconfiguration management table 410 in each of the connection apparatuses4 and 5 in this embodiment. The table 410 is a table for managing zoneconfiguration which prohibits communication between specific port IDsfrom being referred to from a different port ID and has columns of zoneIDs 4101 and port IDs 4102.

In response to a zone creation instruction from the management computer1, a management program 422 creates an entry for the zone configurationmanagement table 410 and stores a unique zone ID 4102 in the connectionapparatus and port IDs 4102 to join the zone to the zone configurationmanagement table 410. The data I/O program 421 refers to this table andtransfers a request from some port ID only to the port IDs belonging tothe zone.

FIG. 34 is a drawing illustrating a configuration example of amanagement communication I/F address management table 420 in each of theconnection apparatuses 4, 5, and 6 in this embodiment. The table 420stores the address 4201 of a management communication I/F 46. At theinstallation of a connection apparatus to the computer system, theadministrator sets the value in the table 420.

FIG. 35 is a diagram illustrating a process flow of adding a hostcomputer 3 in the computer system in this embodiment. When a hostcomputer 3 is wire connected to the connection apparatus 4, the data I/Oprogram 421 in the connection apparatus 4 detects the connection,obtains the port ID of the connection source, specifically, the port ID3102 of the host computer, from the host computer 3, stores it in theport ID 4002 in the connection apparatus management table 400, and setsthe value ON to the lamp status 4003 (S1001).

Next, the administrator identifies the management communication I/Faddress 3101 and the port ID 3102 of the host computer 3 using the inputapparatus 39 and the image output apparatus 38 in the host computer 3(S1002). The administrator inputs the obtained information using theinput apparatus 19 in the management computer 1 (S1003).

The host computer management program 123 in the management computer 1stores inputted information to the host IP 1602 in the host computermanagement table 160 and the port ID 1701 in the connectivity-from-hostmanagement table 170. The host computer management program 123 lists theport IDs 1105 and the virtual port IDs 1106 in the storage system portmanagement table 110 and stores them to the connectable port ID 1703 inthe connectivity-from-host management table 170 (S1004).

Then, for checking connection of the host computer to the connectionapparatus 4, the host computer management program 123 transmits theinputted port ID of the host computer 3 together with a connection checkrequest to the management communication I/F address 1503 of an entry(connection apparatus) containing the value “for host” in the use 1504in the connection apparatus management table 150.

The management program 422 in the connection apparatus 4 searches theport IDs 4002 in the connection apparatus management table 400 for thereceived port ID and responds about the existence. If the received portID exists in the connection apparatus management table 400, it meansthat the port (host computer 3) is connected to the connection apparatus4. This connection check may be performed by obtaining a list ofconnection statuses of the physical ports provided to the managementcommunication I/F in the connection apparatus, for example an FC switch,and searching the obtained list for the port ID (S1005).

The host computer management program 123 in the management computer 1checks the received response (S1006). If the port of the host computer 3is not connected to the connection apparatus 4, the host computermanagement program 123 stores a value indicating a connection error inthe connection apparatus connectivity 1702 in the connectivity-from-hostmanagement table 170 and outputs an error to the image output apparatus18 to terminate the process (S1010).

If the port is connected to the connection apparatus 4, the hostcomputer management program 123 changes the value of the connectionapparatus connectivity 1702 into “checked”. The connection apparatusmanagement program 122 transmits a request to create a zone among theconnectable ports 1703 of the same entry and the port ID 1701 of thehost to the connection apparatus 4. The management program 422 in theconnection apparatus 4 stores the received port IDs to the port ID 4102in the zone management table 410 and responds to the management computer1 to report the creation of the zone (S1007). The zone creation (S1007)may be omitted.

For checking connection between the storage systems 2 and the hostcomputer 3, the storage system management program 121 in the managementcomputer 1 refers to the management communication I/F addresses 1008 inthe storage system management table 100 and transmits the port ID 1701of the host computer 3 to the addresses of the storage systems 2 in allof the entries. FIG. 35 illustrates an example of issuing requests totwo storage systems 2A and 2B.

The operation management program 2214 in each storage system 2 requeststhe connection apparatus 4 to check whether the own ports can connect tothe received port ID of the host computer 3. Specifically, the operationmanagement program 2214 transmits a list of the port ID of the addedhost computer and the own port ID and virtual port IDs to the connectionapparatus 4 with a connection check request.

The connection apparatus 4 refers to the connected equipment managementtable 400 and checks for the received port ID of the host computer 3,and the port ID and virtual port IDs of the storage system (S1008). Theconnection apparatus 4 further refers to the zone configurationmanagement table 410 for checking the permission of connection.

If the ID of a port (physical port or virtual port) of the storagesystem 2 exists in the connected equipment management table 400 with theport ID of the host computer 3 and they belong to the same zone in thezone configuration management table 410, the port of the storage system2 is connectable to the host computer 3. If either condition is notsatisfied, they cannot connect to each other.

The connection apparatus 4 returns a response to the storage systems 2about the permission of connection between each port (a port ID or avirtual port ID) of the storage systems 2 and the port of the added hostcomputer 3. This connection check may be performed by a discoveryfunction of a designated port on a fibre channel. The managementcomputer may directly instruct the connection apparatus 4 to checkconnection between the host computer 3 and the storage systems 2.

The storage system management program 121 in the management computer 1sequentially stores check results received from the storage systems 2 onthe ports to the column of connectivity 1704 in theconnectivity-from-host management table 170 to terminate the process ofadding a host computer (S1009). The connection apparatus 4 may send thecheck result to the management computer 1 without the storage system 2.As explained above, the system conducts connection check in adding ahost computer 3, so that a wiring mistake in installing a host computercan be prevented and workload of the administrator can be reduced.Moreover, it enables automatic selection of a storage system connectedfrom a host computer in volume creation and volume migration, so thatworkload of the administrator in operation can be reduced.

FIG. 36 is a diagram illustrating a flow of a process of adding astorage system 2 in the computer system in this embodiment. Wheninstalling a storage system 2, the administrator wire connects ports forhost connection to the connection apparatus 4 and ports for migration tothe connection apparatus 5.

Each of the data I/O programs 421 in the connection apparatuses 4 and 5detects connection; obtains the port IDs of the connection source,specifically, the port IDs 2304 or the virtual port IDs 2305 of thestorage system, from the storage system 2; stores them to the port ID4002 in the connected equipment management table 400; and changes thevalues in the lamp status 4003 from OFF to ON (S1101, S1102).

Next, the administrator identifies the management communication I/Faddress 2801, the vendor name 2001, the system model name 2101, and theserial number 2201 using the input apparatus 29 and the image outputapparatus 28 in the storage system 2 (S1103).

The administrator inputs the obtained address, vendor name, system modelname, and serial number using the input apparatus 19 of the managementcomputer 1. Specifically, the administrator adds a new entry to thestorage system management table 100 and inputs information to themanagement communication I/F address 1008, the storage system vendorname 1002, the storage system model name 1003, and the storage systemserial number 1004 (S1104).

The operation management program 124 in the management computer 1 make aquery for the port IDs to the management communication I/F address 1008in the storage system 2. The operation management program 2214 in thestorage system 2 returns the values in the relevant fields for theentries in the storage system port management table 230.

The operation management program 124 in the management computer 1 storesthe received contents of the storage system port management table 230 tothe storage system port management table 110. Specifically, it storesthe values of the data I/O communication I/F number 2301 to the data I/Ocommunication I/F number 1102, the values of the use 2303 to the use1103, the values of the port ID 2304 to the port ID 1105, and the valuesof the virtual port ID 2305 to the virtual port ID 1106.

The operation management program 124 assigns virtual data I/Ocommunication I/F numbers to the received entries and stores them in thefields for the virtual data I/O communication I/F number 1104.Furthermore, it sends the assigned virtual data I/O communication I/Fnumbers to the storage system 2. The operation management program 2214in the storage system 2 stores the received virtual data I/Ocommunication I/F numbers in the fields for the virtual data I/Ocommunication I/F number 2302.

Then, the operation management program 124 lists the port IDs 1105 andthe virtual port IDs 1106 of the entries containing the values of “forhost” in the use 1103 in the storage system port management table 110and registers them in the connectable port ID 1703 in theconnectivity-from-host management table 170. Furthermore, it sets“unchecked” to the connectivity 1704 of each entry.

The operation management program 124 further adds entries to theconnectivity-between-storages management table 180, lists the port IDsof the entries containing the values of “for migration” in the use 1103in the storage system port management table 110 and stores them in theport ID 1802. In addition, it sets “unchecked” to the connectivity 1803of each entry.

Next, the connection apparatus management program 122 in the managementcomputer 1 requests the connection apparatus 4 to check connection onthe entries containing the value “unchecked” in the connectivity 1704 inthe connectivity-from-host management table 170, and the connectionapparatus 5 to check connection on the entries containing the value“unchecked” in the connectivity 1803 in theconnectivity-between-storages management table 180.

The check method by the connection apparatuses 4 and 5 (S1105, S1106)are the same as the method explained at S1005; the connectionapparatuses 4 and 5 search the port IDs 4002 in the connected equipmentmanagement table 400 for the received IDs and returns the result. Theconnection apparatus management program 122 stores the result of checkfrom the connection apparatus 4 to the connectivity 1704 and the resultof check from the connection apparatus 5 to the connectivity 1803. Thisconnection check is a check of connection between the added storagesystem 2 and the connection apparatuses 4, 5. The connection apparatusmanagement program 122 stores “physical connection checked” (not shownin FIG. 18 and FIG. 19) to the fields of ports whose normal connectionis checked in the columns of connectivity 1704, 1803.

The connection apparatus management program 122 checks the contents ofthe connectivity 1803 (S1107) and if it is “connection disabled” (NO atS1107), it outputs an error and terminates the process (S1116). Theconnection apparatus management program 122 checks the value of theconnectivity 1704 (S1107) and if all of the newly added port IDs(including virtual port IDs) are “connection disabled” (NO at S1107), itoutputs an error and terminates the process (S1116).

If there is no problem with the connectivity (YES at S1107), theconnection apparatus management program 122 in the management computer 1transmits the list of the port IDs 1701 and the connectable port IDs1703 in the connectivity-from-host management table 170 to theconnection apparatus 4 to configure a zone in the connection apparatus 4and the connection apparatus 4 creates zones (S1108). The connectionapparatus management program 122 transmits the list of the port IDs 1802in the connectivity-between-storages management table 170 to theconnection apparatus 5 and the connection apparatus 4 creates a zone(S1109). The methods at S1108 and S1109 are the same as the methodexplained at S1007. The process of creating a zone (S1108 or S1109) doesnot need to be performed.

The storage system management program 121 in the management computer 1transmits the port IDs 1701 of the host computers 3 of entriescontaining the value “physical connection checked” in the connectivity1704 (connectivity between a host port and a storage port) in theconnectivity-from-host management table 170 to the managementcommunication I/F address of the storage system 2 of the entries withreference to the management communication IF addresses 1008 in thestorage system management table 100.

The storage system management program 121 can locate the entry(management communication IF address) in the storage system managementtable 100 from the entries in the connectivity-from-host managementtable 170 with reference to the storage system port management table110.

The operation management program 2214 in the storage system 2 requeststhe connection apparatus 4 to check whether its own ports (portsidentified by port IDs or virtual port IDs) can connect to the ports ofthe host computers 3 indicated by the received port IDs. The method ofthis request is the same as the method of request in the process ofadding a host computer 3.

The connection apparatus 4 executes connection check responsive to thecheck request from the storage system 2. The method of the connectioncheck by the connection apparatus 4 is the same as that in S1008 in theprocess of adding a host computer 3. The connection apparatus 4 returnsa response about the permission of connection of the storage system 2 tothe other ports to the storage system 2 (S1110).

The storage system 2 returns the result of check on the permission ofconnection received from the connection apparatus 4 to the managementcomputer 1. The storage system management program 121 in the managementcomputer 1 sequentially stores the received results of check on theconnectivity of the ports of the storage system 2 to the connectivity1704 in the connectivity-from-host management table 170 (S1111).

Next, the management computer 1 checks connection between storagesystems. The storage system management program 121 in the managementcomputer 1 locates the management communication I/F address of the newlyadded storage system 2 with reference to the column of the managementcommunication I/F addresses 1008 in the storage system management table100.

The storage system management program 121 transmits the values of theport IDs 1802 of the entries containing the value “physical connectionchecked” in the connectivity 1803 in the connectivity-between-storagesmanagement table 180 and the port ID to which the table 180 is related(of the port for migration in the newly added storage system) to thelocated management communication I/F address together with a connectioncheck request. As explained with reference to FIG. 19, theconnectivity-between-storages management table 180 stores information onconnectivity of some port for migration to other ports for migration indifferent storage systems.

The operation management program 2214 in the newly added storage system2 requests the connection apparatus 5 to check whether the own port IDfor migration informed of can connect to the ports of the other storagesystems informed of. This request accompanies the above-described portIDs transmitted to the added storage system.

The management program 422 in the connection apparatus 5 checksconnection between the ports for migration informed of. The methodthereof is the same as the one in S1005 explained with reference to theflowchart of FIG. 35; for example, it determines the connectivity withreference to the existence of the port ID in the connected equipmentmanagement table 400. The management program 422 returns a responseabout the permission of connection to the storage system 2 (S1112).

The storage system 2 returns the result received from the connectionapparatus 5 to the management computer 1. The storage system managementprogram 120 sequentially stores the received results of check in theentries to the fields for the connectivity 1803 in theconnectivity-between-storages management table 180 (S1113). The storagesystem 2 transfers the results to the management computer 1. Although,in this configuration, the connection apparatuses 4, 5 send theconnection check results to the management computer 1 via the storagesystem, they may send the check results to the management computer 1directly. The management computer 1 may directly instruct the connectionapparatuses 4, 5 to check the connection between the host computer 3 andthe storage system 2 and the connection between the storage systems 2,respectively.

After confirmation of the normal connection (receiving the check resultindicating the normal connection), the storage system management program121 transmits the default virtual vendor name 1901 for a default virtualvendor name 2002, the default virtual model name 1902 for a defaultvirtual model name 2102, the default virtual serial number 1903 for adefault virtual serial number 2202, and the virtual data I/Ocommunication I/F number 1104 for a virtual data I/O communication I/Fnumber 2302. As described above, these default values enable the addedstorage system to function as a storage system integrated with the otherstorage systems. The default values may be provided to the added storagesystem 2 before the connection check.

The operation management program 2214 in the storage system 2 stores thereceived values to the fields for the default virtual vendor name 2002,the default virtual model name 2102, the default virtual serial number2202, and the virtual data I/O communication I/F number 2302 (S1115).

The storage system management program 121 stores the assigned values tothe default virtual vendor name 1005, the default virtual model name1006, and the default virtual serial number 1007 in the storage systemmanagement table 100, and the virtual data I/O communication I/F number1104 in the storage system port management table 110, and the process ofadding a storage system 2 is terminated (S1114).

In this way, this embodiment can easily add a storage system 2 withoutstopping services to the host computers 3. The system conductsconnection check between storage systems and to the host computers inadding a storage system 2, so that a wiring mistake in installing astorage system (scaling out) can be prevented and an error is preventedfrom occurring during system operation. Furthermore, the system conductsconnection check to achieve reduction in workload of the administrator.

FIG. 37 is a diagram illustrating a process flow of deleting a storagesystem 2 in the computer system in this embodiment. This example deletesthe storage system 2A from the computer system. First, the administratorissues an instruction to delete the storage system 2A through theoperation management program 124 in the management computer 1 (S1201).

The storage system management program 121 in the management computer 1refers to the storage system usage management table 130 to compare thetotal amount of the amount of usage 1304 with the total amount of thecapacity 1302 of the storage systems except for the storage system 2A tobe deleted (S1202). If the total of the amount of usage 1304 is greater(NO at S1202), the operation management program 124 outputs an error tothe image output apparatus 18 to terminate the process (S1209).

If the rest of the capacity 1302 is greater (YES at S1202), the storagesystem management program 121 refers to the virtual storage systemvolume management table 140, picks up volumes of entries in which thestorage system ID 1405 contains the ID of the storage system 2A to bedeleted, and sorts them in order from the one having the smallest valuein the amount of usage 1403 (S1203). This order is the order ofexecution of migration.

Various methods of determining the order of migration can be proposed.Values to be referenced may be different from those in this example aslong as they are the values that can be obtained at the host computers3, the connection apparatus 4, and the connection apparatus 5 and thatthe management computer 1 can collect via the connection apparatus 6.

The storage system management program 121 instructs the storage system2A to migrate the volumes sequentially in the above-described order ofmigration. The storage system 2A migrates a designated volume to thestorage system 2B (S1204).

The volume management programs 2213 in the storage systems 2A and 2Breplicate the data in the target volume in the storage system 2A to avolume in the storage system 2B. The volume management program 2213 inthe storage system 2A deletes, and the volume management program 2213 inthe storage system 2B adds the relevant entries in the respective volumemanagement tables 240. Furthermore, the program 2213 in the storagesystem 2A deletes, and the program 2213 in the storage system 2B adds,the corresponding virtual port ID in their respective storage systemport management tables 230.

Upon receipt of a notice that migration of a designated volume ends fromthe storage system 2A, the storage system management program 121 updatesthe values of the relevant entry in the virtual storage system volumemanagement table 140. Furthermore, it changes the corresponding virtualport ID in the storage system port management table 110 from an entry ofthe storage system 2A into an entry of the storage system 2B.

The storage system management program 121 refers to the virtual storagesystem volume management table 140 to check whether an entry (volume)exists or not in which the storage system ID 1405 indicates the storagesystem 2A (S1205). If any volume remains (YES at S1205), the storagesystem management program 121 returns to S1203.

If no volume remains (NO at S1205), the connection apparatus managementprogram 122 in the management computer 1 refers to the storage systemport management table 110, informs the connection apparatuses 4 and 5via the connection apparatus 6 of the port ID 1105 and the virtual portIDs 1106, and requests deletion of them.

The management programs 422 in the connection apparatuses 4 and 5 deletethe notified port ID 4002 from their connected equipment managementtables 400 (S1206, S1207) and change the lamp status 4003 into OFF. Upondetection of the change of the lamp status 4003 into OFF, eachmanagement program 422 turns off the link lamp 48. The managementprogram 422 deletes the notified value of the port ID from the column ofport ID 4102 in the zone management table 410.

The storage system management program 121 in the management computer 1deletes entries including the ID of the deleted storage system 2A fromthe storage system management table 100, the storage system portmanagement table 110, the storage system usage management table 130, theconnectivity-from-host management table 170, and theconnectivity-between-storages management table 180 (S1208). Theadministrator pulls out wires for the data I/O communication I/F 45 withthe link lamps 48 OFF in the connection apparatuses 4 and 5 to terminatethe deletion of the storage system 2A.

As described above, this configuration achieves deletion of a storagesystem 2 from the computer system without stopping services to the hostcomputers 3. Furthermore, potential of mistakes of manual works inpulling out wires can be reduced.

FIG. 38 is a diagram illustrating a flow of a process of creating avolume in the computer system in this embodiment. In this description, aprocedure of creating a volume whose volume type is normal is explained.The administrator inputs an instruction to create a volume through theoperation management program 124 in the management computer 1. Theadministrator inputs the capacity of the volume, the volume type (in theexplanation on FIG. 38, normal), and the host computer 3 to be use forto make an instruction to create a volume (S1301).

The storage system management program 121 in the management computer 1checks whether a host computer 3 to be used for (host ID) is specifiedor not with reference to the inputted information (S1302). If no hostcomputer 3 is specified (NO at S1302), the procedure proceeds to S1304.If some host computer 3 is specified (YES at S1302), the storage systemmanagement program 121 obtains the value of the host-side port ID 1603from the entry containing the value of the specified host ID 1601 in thehost computer management table 160.

The storage system management program 121 searches the column of theport ID 1701 in the connectivity-from-host management table 170 for theobtained value and, out of the matching entry, obtains values ofconnectable port IDs 1703 (port IDs of storage systems) of entriescontaining the value “checked” in the connectivity 1704 out of theentries matching the obtained value. This operation prevents troublecaused by no connection.

Next, the storage system management program 121 searches the columns ofport ID 1105 and virtual port ID 1106 in the storage system portmanagement table 110 for entries including the obtained port ID andlists the IDs of the storage systems except for the storage systemswhich do not have a connectable port ID (S1303).

Then, the storage system management table 121 refers to the storagesystem usage management table 130 with respect to the listed storagesystems and selects a storage system of which a value obtained bydeducting the amount of usage 1304 from the capacity 1302 is thelargest, preferably (S1304). If there is no storage system which has thespecified capacity, it is an error.

Various methods of determining the storage system in which a volume isto be created can be proposed. Values to be referenced may be differentfrom those in this example as long as they are the values that can beobtained from the storage systems 2, the host computers 3 and theconnection apparatuses 4 and 5 and that the management computer 1 cancollect via the connection apparatus 6.

The storage system management program 121 refers to the columns ofvirtual volume numbers 1401 in the virtual volume management table 140and assigns a virtual volume number which is not a duplicate to thenewly created volume (S1305). Through this operation, the volume isuniquely identified in the computer system. The storage systemmanagement program 121 notifies the storage system 2 selected at S1304of the assigned virtual volume number and the information specified bythe administrator and instructs it to create a volume.

The volume management program 2213 in the storage system 2 that receivesthe instruction selects, for example, a media ID 2701 with which thedifference between the capacity 2704 and the amount of usage 2705 is thegreatest, creates a volume having the specified size in the media, andupdates the media management table 270 (S1306). If there is no mediawhich can store the specified size of volume, it is an error.

The volume management program 2213 adds an entry in the volumemanagement table 240, assigns a volume ID unique in the storage system,stores the capacity, the type, the virtual volume number specified bythe management computer 1 in the fields for the capacity 2402, the type2403, and the virtual volume number 2405, respectively, and further,stores the media ID assigned at S1306 in the field for the media ID2404.

The volume management program 2213 copies the values of the defaultvirtual vendor name 2202, the default virtual model name 2102, anddefault virtual serial number 2202 and stores them in the fields for thevirtual vendor name 2406A, the virtual model name 2406B, and virtualserial number 2406C (S1307). Through this operation, each storage system2 can return common (same) storage identification information inresponding to a request for volume information from a host computer 3.

The operation management program 2214 in the storage system 2 notifiesthe management computer 1 of the volume ID 2401 and media ID 2404 on thecreated volume. The operation management program 124 in the managementcomputer 1 stores information on the created volume in the volumemanagement table 140 to terminate the creation of a volume (S1308).

FIG. 39 is a diagram illustrating a flow of a process of creating a thinprovisioning pool in the computer system in this embodiment. Theadministrator executes a process of creating a pool while specifying apool name through the operation management program 124 in the managementcomputer 1. The operation management program 124 adds an entry in thestorage system pool management table 120 and stores the specified poolname in the pool name 1201 (S1401).

The administrator refers to the virtual storage system volume managementtable 140 and selects volumes to be included in the thin provisioningpool using the operation management program 124 (S1402). In this system,volumes can be selected from different storage systems 2. Aconfiguration where a pool includes volumes irrespective of physicalboundaries among storage systems achieves more appropriate pool capacitymanagement.

The operation management program 124 transmits an instruction to createa thin provisioning pool to the storage systems 2A and 2B with respectto each selected volume, with reference to the virtual storage systemvolume management table 140. It transmits the instruction to create apool even to the storage system 2B which does not have a selectedvolume.

The pool management program 2212 in the storage system 2A adds an entryto the thin provisioning pool management table 250 and stores thespecified pool name to the pool ID 2501 (S1403).

The pool management program 2212 in the storage system 2A searches thevirtual volume numbers 2405 in the volume management table 240 for anentry containing the volume specified by the management computer 1(S1405).

The pool management program 2212 stores the volume ID 2401 of a matchingentry to the constituent volume ID 2504 in the thin provisioning poolmanagement table 250; and stores the capacity 2402 to the capacity 2505.The pool management program 2212 divides the added volume into pages,assigns numbers to the pages, and stores a created list of the numbersto the page number 2507. Furthermore, it sets the value “unallocated” tothe status 2508 for each page (S1406). Then, the operation managementprogram 2214 transmits a completion report to the management computer 1.The storage system 2B performs the same processes as S1403 and S1406(51404 and S1407).

Upon receipt of complete reports from the storage systems 2A and 2B, thestorage system management program 121 in the management computer 1stores information on each storage system in the storage system poolmanagement table 120. Specifically, it stores information on the storagesystem identified with the storage system ID 1204 to the correspondingentry. The information to be stored is the capacity 1205A of the thinprovisioning pool in the storage system, the constituent volume IDs1207A, and their capacity 1207B. The storage system management program121 further stores the value obtained by summing the values of thecapacities 1205A to the total capacity 1202 and terminates the processof creating a thin provisioning pool (S1408).

FIG. 40 is a diagram illustrating a flow of a process of creating a thinprovisioning volume in the computer system in this embodiment. In thisdescription, a procedure of creating a volume whose volume type is thinprovisioning will be explained.

The administrator inputs an instruction to create a volume through theoperation management program 124 in the management computer 1. Theadministrator inputs a pool name, the capacity of the volume, the volumetype (in the explanation on FIG. 40, thin provisioning), and the hostcomputer 3 to be used for to make an instruction of creation of a volume(S1501).

The storage system management program 121 in the management computer 1checks whether a host computer 3 to use (access) the volume is specifiedor not (S1502). If no host computer 3 is specified (NO at S1502), theprocedure proceeds to S1504. If some host computer 3 is specified (YESat S1502), the storage system management program 121 obtains the valueof the host-side port ID 1603 of the host computer 3 with reference tothe host computer management table 160.

The storage system management program 121 searches the port IDs 1701 inthe connectivity-from-host management table 170 for the port ID of thespecified host computer 3 and obtains port IDs (port IDs of storagesystems) of the entries containing the value “checked” in theconnectivity 1704 in the connectable port IDs 1703 of the entry matchedwith the host computer 3.

Next, the storage system management program 121 searches the port IDs1105 and virtual port IDs 1106 in the storage system port managementtable 110 for entries including the obtained port IDs to obtain thestorage system IDs thereof. The storage system management program 121lists the storage system IDs except for the storage systems which do nothave a connectable port ID (S1503).

Then, the storage system management table 121 refers to the storagesystem pool management table 120 to locate entries of the listed storagesystems with the storage system IDs 1204, and selects a storage systemfor which the value obtained by deducting the amount of usage 1205B fromthe capacity 1205A is the greatest, preferably (S1504).

The storage system management program 121 in the management computer 1refers to the virtual volume numbers 1401 in the virtual storage systemvolume management table 140 and assigns an unduplicated virtual volumenumber to the new thin provisioning volume (S1505).

The storage system management program 121 informs the selected storagesystem 2 of the assigned virtual volume number and information specifiedby the administrator and instructs the storage system 2 to create thevolume.

The volume management program 2213 in the storage system 2 adds an entryto the volume management table 240 in response to the instruction tocreate a volume. The volume management program 2213 assigns a uniquevolume ID in the storage system to the new entry and stores thecapacity, the type, and the virtual volume number specified by themanagement computer 1 to the fields for the capacity 2402, the type2403, and the virtual volume number 2405, respectively (S1506).

The volume management program 2213 copies the values of the defaultvirtual vendor name 2002, the default virtual model name 2102, and thedefault virtual serial number 2202 and stores them to the fields for thevirtual vendor name 2406A, the virtual model name 2406B, and the virtualserial number 2406C, respectively (S1507).

The operation management program 2214 in the storage system 2 reportsthe values of the volume ID 2401 and the media ID 2404 of the createdvolume to the management computer 1. The operation management program124 in the management computer 1 stores the information on the createdvolume in the volume management table 140 to terminate the process ofcreating a volume (S1508).

FIG. 41 is a diagram illustrating a flow of a process of setting a portto a volume in the computer system in this embodiment. The administratorinputs an instruction to map a port to a volume through the operationmanagement program 124 in the management computer 1.

The volume is selected from the virtual storage system volume managementtable 140 and is specified with the virtual volume number 1401. The portis selected from entries containing the value “for host” in the use 1103in the storage system port management table 110 and specified with thevirtual data I/O communication IF number 1104. The specified port numberis stored in the virtual port number 1408A (S1601) by the operationmanagement program 124. Through it, each storage system 2 can return thecommon (same) storage identification information in response to arequest for volume information from a host computer 3.

The storage system management program 121 checks whether the storagesystem ID 1405 of the selected volume in the virtual storage systemvolume management table 140 is the same as the storage system ID 1101for the selected port in the storage system port management table 110(S1602).

It they are the same (YES at S1602), the storage system managementprogram 121 transmits an instruction to set a port to the storage system(in this example, the storage system 2A). The volume management program2213 in the storage system 2A searches the virtual data I/Ocommunication I/F numbers 2302 in the storage system port managementtable 230 for the specified virtual data I/O communication I/F number tolocate the data I/O communication I/F number 2301.

The volume management program 2213 searches the virtual volume numbers2405 in the volume management table 240 for the specified virtual volumenumber and stores the value of the data I/O communication I/F number2301 to the field for a port number 2408A of the entry found. The volumemanagement program 2213 stores the specified data I/O communication I/Fnumber to the field for the virtual port number 2407A and transmits acompletion report to the management computer 1 to terminate the mappingof a port to a volume (S1603).

If the storage system of the volume differs from the storage system ofthe port at S1602 (NO at S1602), the storage system management program121 uses a known external storage system attachment technique betweenthe storage system 2A including the volume and the storage system (inthis example, storage system 2B) including the port (communicationinterface) to map the volume in the storage system 2A to the storagesystem 2B. The external storage system attachment technique is describedin above PTL 1, for example.

The storage system 2B is provided with the above-described volume by thestorage system 2A and processes an access request (a request to readdata or write data) to the volume received from a host computer 3. Thehost computer 3 can read information from or write information to thestorage system 2A via the connection apparatus 5 from the storage system2B.

More specifically, the storage system management program 121 in themanagement computer 1 notifies the storage system 2B of the port ID andthe ID of the target volume (corresponding to the virtual volume number)in the externally connected storage system 2A. The volume managementprogram 2213 in the storage system 2B confirms the connection to thetarget volume and then adds an entry of the volume to the volumemanagement table 240 to manage it.

The storage system management program 2213 in the storage system 2Breceives information on the volume from the volume management program2213 in the storage system 2A via the connection apparatus 6. Althoughnot shown in FIG. 25, the entry of the volume includes the IDs of thestorage system 2A and the port therein. The storage system 2B maps itsown port to the above-described volume responsive to the instructionfrom the management computer 1 in the same way at S1603 (S1604).

In response to an I/O request from a host computer 3 to some volume, thedata I/O program 2211 in the storage system 2B refers to the volumemanagement table 240 and if the I/O request is targeted to an externalvolume (in this example, a volume in the storage system 2A), ittransfers the request to the port ID and the volume ID.

The data I/O program 2211 in the storage system 2A which receives thetransferred I/O request reads data from the volume or writes data to thevolume and returns the result to the storage system 2B. The data I/Oprogram 2211 in the storage system 2B transfers the received result tothe host computer 3.

In this way, a host computer 3 in this system can read or write a volumein a storage system via an interface in a different storage system.Since the host computer 3 locates the volume with the same volumeidentification information and storage identification information, itdoes not concern which storage system the volume is located.

Furthermore, to reduce the amount of traffic in the connection apparatus5, the storage system management program 121 may copy information on thespecified volume to a volume in the storage system 2B to migrate thevolume (S1605).

FIG. 42 is a diagram illustrating a flow of setting a port for analternate path to a volume in the computer system in this embodiment.The administrator inputs an instruction to map a port for an alternatepath to a volume through the operation management program 124 in themanagement computer 1. The volume is selected from the virtual storagesystem volume management table 140 and specified with a virtual volumenumber 1401.

The port is selected from entries containing the value “for host” in theuse 1103 in the storage system port management table 110 and specifiedwith a virtual data I/O communication I/F number 1104. The specifiedport number is stored in the alternate virtual port number 1408B by theoperation management program 124 (S1701).

The storage system management program 121 searches the virtual data I/Ocommunication I/F numbers 1104 in the storage system port managementtable 110 for the virtual port number 1408A and the alternate virtualport number 1408B in the virtual storage system volume management table140 for the selected volume and determines whether the storage system 2of the virtual port and the storage system 2 of the alternate virtualport are the same or not (S1702).

If they are the same (YES at S1702), the storage system managementprogram 121 transmits an instruction to set an alternate port to thestorage system 2A. The volume management program 2213 in the storagesystem 2A searches the virtual data I/O communication I/F numbers 2302in the storage system port management table 230 for the specifiedvirtual data I/O communication I/F number and locates the data I/Ocommunication I/F number 2301.

The volume management program 2213 searches the virtual volume numbers2405 in the volume management table 240 for the specified virtual volumenumber and stores the value of the data I/O communication I/F number2301 to the alternate port number 2408B in the entry found. Furthermore,it stores the specified virtual data I/O communication I/F number to thealternate virtual port number 2407B and transmits a completion report tothe management computer 1 to terminate the mapping of the port to thevolume (S1703).

If the two values are not the same at S1702 (NO at S1702), the storagesystem management program 121 determines whether the storage system ID1405 of the selected volume in the virtual storage system volumemanagement table 140 is the same as the storage system ID 1101 of theselected port in the storage system port management table 110 (S1704).

If the volume and the port belong to different storage systems (NO atS1704), the storage system management program 121 instructs the storagesystem 2B to set up a configuration between the storage system 2Aincluding the volume and the storage system 2B including the alternateport where the storage system 2B can read or write information in thestorage system 2A via the connection apparatus 5 using the externalstorage system technique.

The volume management program 2213 in the storage system 2B sets theselected volume in the storage system 2A to be regarded as a volume inthe storage system 2B as explained with reference to FIG. 41. If thevolume and the port belong to the same storage system (YES at S1704),the external connection between the storage systems 2A and 2B isskipped. The volume management program 2213 in the storage system 2Bthen maps its own port to the volume provided by the storage system 2A(S1705).

In this connection, the storage system 2A has a cache memory 21different from that of the storage system 2B. If I/Os for read or writeoccur from a plurality of ports, data will be corrupted because of theproblem of cache coherency. Accordingly, the cache function should beturned off. The storage system management program 121 instructs thestorage systems 2A and 2B to turn the cache off for the relevantvolumes.

Each of the operation management programs 2214 in the storage systems 2Aand 2B changes the value of the cache allowability 2409 in the volumemanagement table 240 into “unallowable”. In the subsequent I/Oprocessing, when the data I/O program in each storage system refers tothe volume, it processes data I/Os without using the cache memory sincethe value of the cache allowability 2409 is “unallowable”.

As described above, if the volume and the port belong to the samestorage system at S1704 (YES at S1704), the mapping of the volume in thestorage system 2A to the storage system 2B is omitted and the value ofthe cache allowability 2409 for the volume should remain “allowable”.

FIG. 43 is a diagram illustrating a flow of processing a data I/O (datawrite/read) request from a host computer 3 in the computer system inthis embodiment. The operating system 323 in a host computer 3 locates avolume with reference to the connected storage system's volumemanagement table 300 and transmits a data I/O request to the storagesystem 2. The data I/O request includes a read/write request of userdata, and in addition, an I/O request of other information such as portinformation and volume information.

The flowchart of FIG. 43 includes requesting information on a port,requesting information on a volume, and reading or writing user data,but usually, these processes are not executed in series. A host computer3 obtains port information and volume information at predetermined times(for example, periodically) to locate a volume using the information.The port information and the volume information do not need to beobtained every reading or writing of user data.

The operating system 323 of a host computer 3 transmits a portinformation request to each port of each storage system 2 at apredetermined time. The data I/O program 2211 in the storage system 2that receives the request searches the data I/O communication I/Fnumbers 2301 in the storage system port management table 230 for thenumber of its own data I/O communication I/F 25 that receives therequest and obtains the information in the matched entry.

The data I/O program 2211 returns the value of the virtual data I/Ocommunication I/F number 2302 as the port number, the value of thedefault virtual vendor name 2002 as the vendor name, the value of thedefault virtual model names 2102 as the model name, and the value of thedefault serial number 2202 as the serial number (S1801).

The operating system 323 in the host computer 3 transmits a volumeinformation request with a volume ID to each port of each storage system2. The data I/O program 2211 in the storage system 2 that receives therequest searches the virtual volume numbers 2405 in the volumemanagement table 240 for the volume ID received with the request andreturns the virtual model names 2406B and the virtual serial numbers2406C in the matching entry to the host computer 3 (S1802).

In this way, this system is configured to return the default storageidentification information to the host computer 3, so that the hostcomputer 3 can read and write a volume regardless of the storage systemwhere the volume exists.

The operating system 323 in a host computer 3 requests a read or a writeof a volume. The data I/O program 2211 in the storage system 2 searchesthe volume management table 240 for the received volume ID and refers tothe value of the cache allowability 2409 in the matching entry. If thevalue indicates that caching is allowable, the data I/O program 2211processes the I/O using the cache memory; if unallowable, it processesthe I/O without using the cache memory.

If the storage area is short to write to a thin provisioning volume 224,the data I/O program 2211 refers to the thin provisioning managementtable 250 to search for a page with the value “unallocated” contained ina field of the status 2508, and allocates the page. It adds aconstituent volume ID 2605 and a page number 2606 in the entry includingthe volume ID 2601 in the thin provisioning volume management table 260and adds a page size to the amount of usage (S1803, S1804).

The management computer 1 sends a status check request to each storagesystems 2 at constant intervals, obtains use of the storage systems anduse of the volumes, and updates the internal management tables. Thisprocedure has already been described.

FIG. 44 is a diagram illustrating a process flow of leveling theresources in the computer system in this embodiment. The storage systemmanagement program 121 in the management computer 1 searches for atarget volume of migration. Specifically, referring to the storagesystem usage management table 130, it searches for an entry in which thepercentage of the amount of usage 1304 to the total capacity 1302exceeds the capacity threshold 1303 in each storage system ID 1301(S1901).

If such a storage system 2A exists that the percentage of the amount ofusage is more than the capacity threshold, the storage system managementprogram 121 searches the storage system IDs 1405 in the virtual storagesystem volume management table 140 for an entry containing the storagesystem ID. The storage system management program 121 selects anarbitrary volume from the entries containing the value “normal” in thevolume type 1404 in the volumes of the matching entry as a migrationtarget (S1902).

The storage system management program 121 selects a storage system whichhas remaining capacity enough for migration of the selected volume andis accessible by a host computer 3 that accesses the selected volume asthe migration destination storage system 2B. This configurationdefinitely prevents a trouble that a host computer 3 is inaccessible tothe volume. If a plurality of storage systems exist that satisfy theserequirements, it is preferable to select the storage system having theleast amount of usage 1304.

For example, the storage system management program 121 uses thefollowing method to find a storage system to which a host computer 3 canconnect. The storage system management program 121 locates a virtualport number 1408A that connects to the selected volume with reference tothe virtual storage system volume management table 140 and locates aport ID 1105 or a virtual port ID 1106 associated with the virtual portnumber with reference to the storage system port management table 110(S1903).

The storage system management program 121 further locates a port ID 1701of the host computer 3 that connects to the located port or virtual portwith reference to the host connectivity management table 170. A storagesystem having a port ID included in the column of the connectable portIDs 1703 for the located port ID 1701 in the host connectivitymanagement table 170 is selected as the migration destination (S1904).

The storage management program 121 further searches the storage systempool management table 120 for an entry of which the percentage of theamount of usage 1205B to the capacity 1205A exceeds the capacitythreshold 1205C and obtains the storage system ID of the entry. Inaddition, the storage system management program 121 searches for anentry of which the value of the IOPS 1206A exceeds the performancethreshold 1206B and obtains the storage system ID of the entry (S1905).

The storage system management program 121 searches the storage systemIDs 1405 in the virtual storage system volume management table 140 forentries of the storage system of which the amount of usage or the IOPSexceeds the threshold. In the volumes of the storage system (entries),it selects an arbitrary volume from the entries containing the value“thin provisioning” in the volume type 1404 as a migration target(S1906).

The storage system management program 121 selects a storage system thathas remaining capacity enough for the selected volume to be migrated andis accessible by a host computer 3 that accesses the selected volume asthe migration destination storage system 2B. If a plurality of storagesystems exist that satisfy these requirements, the program 121 selectsthe storage system having the least amount of usage 1304. The method ofselecting a migration destination accessible by the host computer 3 isthe same as the above-described migration method for a normal volume.

The storage systems 2A and 2B conduct migration of the selected volumesfrom the storage system 2A to the selected migration destination storagesystem 2B (S1907). The method of migration has been described above.

Through this process, the resources in the storage systems are leveledto achieve load balancing. Furthermore, automatic migration to a storagesystem 2 accessible by a host computer 3 is achieved.

FIG. 45 is a drawing illustrating a flow of a process of adjusting thecapacity of a thin provisioning pool in the computer system in thisembodiment. In a computer system in which a plurality of storage systemsconfigure a virtual storage system, volumes created for thinprovisioning under management are allocated pages from the volumes(constituent volumes) that constitute thin provisioning pools in thestorage systems and store data written from host computers 3.

In this process, the amount of data and the frequency of writing fromhost computers 3 are different in every volume, so that the remainingcapacities of the storage systems 2 in a thin provisioning pool changewith time, resulting in variation between the capacities.

In this computer system, the administrator manages the total amount andthe amount of usage of a pool using the storage system pool managementtable 120 in the management computer 1; even if some storage systembecomes in short of the capacity because a volume in the storage systemis frequently written, there are storage systems having sufficientremaining capacities in the entire pool, so that the capacities can betransferred.

Meanwhile, for capacity management using the total capacity 1202 and theamount of usage 1203 in the storage system pool management table 120,transfer of capacities among the storage systems is necessary. Now withreference to FIG. 45, a flow of capacity transfer will be describedwhere the capacity of a thin provisioning pool in the storage system 2Bis short and the storage system 2A has a sufficient remaining capacity.

In the process explained with FIG. 44, the storage system managementprogram 121 calculates the amount of usage 1205B in relation to thecapacity 1205A every storage system ID 1204 in the storage system poolmanagement table 120. For example, if there is a storage system of whichthe percentage of the amount of usage 1205B to the capacity 1205Aexceeds the capacity threshold 1205C, the computer system performsreconfiguration of constituent volumes of a thin provisioning pool.

If such a storage system 2B exists in a pool, the storage systemmanagement program 121 selects the ID 1204 of a storage system 2A inwhich the percentage of the amount of usage 1205B to the capacity 1205Ais the lowest in the pool (pool name 1201), for example.

The storage system management program 121 further selects an arbitraryvolume from the constituent volume IDs 1207A in the selected storagesystem 2A and instructs the selected storage system 2A to release thevolume from the thin provisioning pool volumes (S2001).

To remove the designated volume from the thin provisioning pool, thepool management program 2212 of the storage system 2A refers to the thinprovisioning pool management table 250 and copies the data of the pagenumbers 2507 of the constituent volume ID 2504 for the pool ID 2501 toanother constituent volume. Moreover, it changes the constituent volumeIDs 2605 and the page numbers 2606 in the thin provisioning volumemanagement table 260, and changes the status 2508 from “allocated” to“unallocated” (S2002).

When all of the statuses 2508 of the volumes are changed into“unallocated”, the pool management program 2212 deletes the entry of thevolume and reduces the capacity 2505 of the constituent volume from thetotal capacity 2502 (S2003).

Upon receipt of a management return of releasing a volume from thestorage system 2A, the storage system management program 121 in themanagement computer 1 instructs the storage system 2B in short of thecapacity to connect to the volume deleted at S2003 using an externalstorage system technique. The method of providing a volume from thestorage system 2A to 2B using the external storage system technique isthe same as the method explained with reference to FIG. 41.

The storage system 2B can read or write the same volume of the storagesystem 2A like the own volumes in itself. The storage system 2B adds thevolume provided by the storage system 2A to the thin provisioning poolas its own volume. The pool management program 2212 in the storagesystem 2B registers the volume in the thin provisioning management table250 with a new constituent volume ID (S2004).

Thereafter, to balance the allocation state within the same pool in thethin provisioning pool management table 250 the pool management program2212 in the storage system 2B may copy data to the pages of the addedvolume and rewrites the constituent volume IDs 2605 and its page numbers2606 in the thin provisioning volume management table 260 (S2005), inaddition to allocating a new page for a new write request when using thenewly added constituent volume.

As described above, this process incorporates a pool volume in adifferent storage system if some storage system providing a pool volumebecomes in short of the capacity. This configuration achievesappropriate management of the capacity of a pool irrespective ofphysical boundaries among storage systems.

As set forth above, this invention has been described in detail withreference to the accompanying drawings. However, this invention is notlimited to the specific configurations but includes variousmodifications and equivalent configurations within the scope of theappended claims. A part of the configurations in this embodiment may beadded, deleted, or replaced with those in the other configurations. Forexample, it is preferable that the system conduct connection check onthe apparatuses but this process may be omitted. It is also preferablethat the system include all of the above-described functions such as thethin provisioning volume function and the external storage systemfunction, but the system may include a part of these functions.

All of the storage systems included in the computer system preferablyhave the common default storage system identification information andonly a part of the storage systems may have the default storage systemidentification information. The above-described configurations andfunctions, for all or a part of them, may be implemented by hardwareobtained by designing integrated circuits, for example. The informationof programs, tables, and files to implement the functions may be storedin a storage device such as a non-volatile semiconductor memory, a harddisk drive, or an SSD, or a computer-readable non-transitory datastorage medium such as an IC card, an SD card, or a DVD.

The invention claimed is:
 1. An information storage system comprising aplurality of storage systems and a management system, wherein: themanagement system is configured to: manage connection informationbetween the plurality of storage systems and a plurality ports of a hostcomputer, and manage capacity information of the plurality of storagesystems; identify a port, which is connected to a migration targetvolume of a migration source storage system in the plurality of thestorage systems, in the plurality of ports of the host computer on thebasis of the connection information; and select a migration destinationstorage system, which is able to be connected to the identified port ofthe host computer and has remaining capacity for the migration targetvolume of the migration source storage system, in the plurality ofstorage systems on the basis of the connection information and thecapacity information, and wherein data of the migration target volume ismigrated from the migration source storage system to the selectedmigration destination storage system.
 2. The information storage systemaccording to claim 1, wherein when the migration destination storagesystem receives a request from the host computer to the migration targetvolume provided by the migration source storage system, the migrationdestination storage system is configured to transfer the request to themigration source storage system, wherein the migration source storagesystem is configured to receive the transferred request and send theresult of the request to the migration destination storage system, andwherein the migration destination storage system is configured totransfer the result of the request to the host computer.
 3. Theinformation storage system according to claim 1, wherein the managementsystem is configured to select the migration source storage system inthe plurality of the storage system on the basis of the capacityinformation, and wherein a ratio of usage capacity in the migrationsource storage system exceeds a predetermined threshold value.
 4. Theinformation storage system according to claim 1, wherein the managementsystem is configured to select the migration source storage system inthe plurality of the storage system on the basis of the capacityinformation, and wherein a ratio of usage capacity in a storage poolformed by storage devices in at least one storage system including themigration source storage system exceeds a predetermined threshold value.5. A management system managing a plurality of storage systems,comprising: a controller and a memory storing connection informationbetween the plurality of storage systems and a plurality ports of a hostcomputer, and manage capacity information of the plurality of storagesystems, wherein the controller is configured to: manage identify aport, which is connected to a migration target volume of a migrationsource storage system in the plurality of the storage systems, in theplurality of ports of the host computer on the basis of the connectioninformation; and select a migration destination storage system, which isable to be connected to the identified port of the host computer and hasremaining capacity for the migration target volume of the migrationsource storage system, in the plurality of storage systems on the basisof the connection information and the capacity information, and instructa data migration for the migration target volume between the migrationsource storage system and the selected migration destination storagesystem.